Pros: Well balanced without excessive bass or treble; comfortable; good soundstage; quite robust
Cons: Not easy to drive (low volume level on portable devices); sensitive to positioning on ear; some resonances in the mids; trebles a little held back
Intro: This is my first review here. I bought these headphones for my son who uses them mainly for gaming and some occasional music listening. I wanted to get him open or at least semi-open types so that he won't be acoustically isolated from his surroundings. I personally use the Beyerdynamic DT770 Pro closed types and, after listening to the AKG 142, I was intrigued to see how well they perform and gave them an audition.
Setup: Audio CDs ripped to flac -> Gmusicbrowser with ALSA running on Linux in a bitperfect configuration -> Asus Xonar Essence STX (using its headphone output) -> AKG K 142 HD -> a pair of ears.
Gershwin - Porgy & Bess, with Ella Fitzgerald and Louis Armstrong
Bach - Brandenburg Concertos 1-6, with The English Concert, Trevor Pinnock
Faure - Requiem, Rundfunkchor Leibzig, Sir Collin Davis
Wynton Marsalis - The Sound of Jazz (live recordings)
Lew Tabackin - Tenority
Woman, Volume II - POP mix
Monserrat Caballe - Puccini Arias
Stravinsky - Le Sacre du Printemps / The Firebird, with the Israel Philharmonic Orchestra, Leonard Bernstein
Frank Zappa - Sheik Yerbouti
Jack DeJohnette - New Directions in Europe
Rachelle Ferrell - First Instrument
Bustan Abraham - Canaan
Guru - Jazzmatazz, Volume 1
Rostropovich - Vivaldi Cello concerto in D minor
Before giving the earphones a real try, I did some listening with my Nexus 4 cell phone to see how the AKG 142 performs on mobile devices. While it's possible to use the AKG on a mobile phone or mp3 player, the volume is probably too low. The semi-open design also limits its use in noisy environments.
The headphones are specified at 55 Ohms but when selecting the <64 Ohm setting in my Asus Xonar Essence card the volume would be too low for auditioning. The 64-300 Ohm did the trick, increasing the volume enough to allow for critical listening. But for those who like to listen real loud, the Asus Xonar Essence needs to be set to 300-600 Ohm. I haven't tested with onboard sound but given my experience with the Xonar Essence this AKG K 142 HD is best used with an amp.
The AKG 142 seems surprisingly flat in the response, perhaps a little forward in the mids. I did some a/b comparisons with the Beyerdynamic DT770. Bass reproduction with the AKG is good, with perhaps a little less punch compared to the DT 770. The most notable difference, however, is in the treble where the AKG sounds laid back and less crisp. It can be easily heard on Jack DeJohnettes album which has lots of cymbals and drum parts. Here I also noticed how critical it is to position the AKG correctly, as the highs can sometimes get blocked. For comparison, by design the DT 770 don't have that problem as they fit over the ear. Listening to some Jazzmatazz volume 1 tracks reveals that the bass is not as tightly controlled as with the DT 770.
Vocal music reproduction is good. Voices sound natural and engaging. The rich mid range definitely contributes to the enjoyment when listening to vocals.
Instrumental music like Bustan Abraham's "Canaan" is played back well, if a little forward sounding. The AKG K 142 HD have an open sound, with the treble just a bit held back.
I best enjoyed the AKG when listening to Jazz. Listening to Lew Tabackin's "Tenority" album put me back to sitting in his concert years ago.
While the AKG 142 are enjoyable, they are no match to the Beyerdynamic DT 770 Pro. The latter produce more detail and better separation. This becomes obvious when listening to classical music.
Sound: While they aren't perfect, they have enough musicality to make them worth listening to. More so when looking at the price. The trebles are a little held back, though, not as crisp as I would wish. See above for more details.
Comfort: The pressure on the ears is a little uncomfortable when wearing glasses. If you don't wear glasses, they are comfortable.
Construction/durability: The headphones make a sturdy impression and so far my son who often carries them in his bag hasn't managed to break them. The cable isn't curled which I would have preferred. Of course, the semi-open design has it's pros and cons.
Conclusion: If you don't want to spend a lot of money, the AKG K 142 HD are worth giving a try. They are best used with an amp to drive them, so they are less suitable for mobile devices.